/*
 * Copyright 2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
package org.spicefactory.lib.expr.impl {

import org.spicefactory.lib.expr.Expression;
	
/**	
 * Represents a literal expression without variable parts.
 * Example: <code>"This is just a literal."</code>
 * 
 * @author Jens Halm
 */
public class LiteralExpression implements Expression {
	
	private var _expressionString:String;
	private var _value:String;
	
	
	/**
	 * Creates a new expression instance.
	 * 
	 * @param expression the expression string
	 */
	public function LiteralExpression (expression:String) {
		_expressionString = expression;
	}
	
	/**
	 * @inheritDoc
	 */
	public function get value () : * {
		if (_value == null) {
			unescapeExpression();
		}
		return _value;
	}

	/**
	 * @inheritDoc
	 */
	public function get expressionString() : String {
		return _expressionString;
	}
	
	private function unescapeExpression () : void {
		if (_expressionString.indexOf("$\\{") == -1) {
			_value = _expressionString;
		} else {
			_value = _expressionString.split("$\\{").join("${");
		}
	}
	
	
}

}